Posted by tizmagik on 04/17/07 23:18

A little closer... I believe this would be the right SQL
theoretically, but this will only work in an Oracle DB or DB that
supports the MINUS operation (MySQL doesnt), so I will try to
reformulate this without using MINUS. I'm guessing it's some sort of
JOIN operation where you check for Nulls and select those that are not
Null...

SELECT B1.CustomerID
FROM Bought B1
WHERE NOT EXISTS (
( SELECT Prefer.ItemID
FROM Prefer, Customer
WHERE Customer.Customer_Name = 'John'
AND Prefer.CustomerID = Customer.CustomerID
) MINUS (
SELECT B2.ItemID
FROM Bought B2
WHERE B2.CustomerID = B1.CustomerID )
)

Any help would be appreciated.

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